usps online printing... easier and cheaper. Also if you have a smart phone theres probably an app and you can scan the label to make it easier for yourself to keep track. They will also pick it up if you print online...

Depends on the weight, but either USPS Priority Mail O-1095 box or the USPS Priority Medium Flat Rate Box. They all come with free tracking. For Adidas shoes or some Nike shoes, you can use the USPS Shoe Box since it fits to size. Order the boxes from the USPS web site which is free. Schedule a pickup on the USPS web site if you live in a house whenever you need to ship something.